Calculation of the streaming potential near a rotating disk

Area of Science:

• Electrochemistry
• Physical Chemistry
• Surface Science

Background:

• Streaming potential measurements are crucial for characterizing interfacial electrical properties.
• Previous theories for rotating disk electrodes in electrolytic solutions showed discrepancies with experimental zeta potential values.
• A factor of two error was consistently observed between theoretical predictions and experimental results for zeta potential.

Purpose of the Study:

• To present a corrected theoretical framework for streaming potential around a rotating disk electrode.
• To identify and rectify the flaw in prior theories that led to experimental discrepancies.
• To reconcile literature data with theoretical predictions by incorporating a more accurate understanding of current flow.

Main Methods:

• Development of a revised theoretical model for streaming potential.
• Analysis of surface current generation and its path within the diffuse layer and bulk solution.
• Comparison of predictions from the new theory with existing experimental data.

Main Results:

• The prior theory underestimated zeta potential by a factor of approximately two due to an incomplete understanding of current flow.
• The corrected theory accurately accounts for the surface current emerging from the diffuse layer and entering the bulk solution at the disk periphery.
• The new theoretical treatment successfully resolves the discrepancy between literature streaming potential data and calculated zeta potential values.

Conclusions:

• A corrected theory for streaming potential in rotating disk systems has been established.
• The revised model provides a more accurate method for determining zeta potential from streaming potential measurements.
• This work resolves a long-standing discrepancy in electrokinetic measurements involving rotating disk electrodes.